Ask any dermatologist and they'll tell you that a serum is a really good thing to add to your skin-care routine. Lighter than moisturizers, they're packed with high concentrations of active ingredients, play nicely with your moisturizer and eye cream, and can treat every skin-care grievance imaginable (dryness, spots, wrinkles). Such powers mean that serums usually come with a hefty price-tag...but there are exceptions. These ten deliver serious skin-saving benefits, without delivering a major blow to your bank account.

Whether it's in a harshly air-conditioned studio or under the beating sun, working out in warm weather is tough on hair and skin. The good news? These miracle-working products—all vetted by fitness and beauty experts—are tougher.